In a principal aspect the present invention relates to a lock and, more particularly, to a lock which is useful as an approved postal box lock.
Postal lock boxes typically include a key-actuated tumbler lock, which enables the postal patron or customer to achieve access to the lock box on a one-time basis. The lock box is designed to permit the postal patron to have one time access to the box in order to remove the contents thereof subsequent to obtaining the lock box key from a postal employee. In such a circumstance, the patron has the opportunity to use an appropriate key obtained from a postal worker to unlock the lock box, release the bolt from the lock box strike and thereafter open the lock box door for access to the contents. Upon opening the lock box door, however, it is desired to capture the customer key in the lock and preclude closing of the lock box door. The patron can then remove the contents of the lock box, leaving the key in the lock box door lock. Thereafter, a post office employee may retrieve the patron or customer key and return it to the post office repository after closing and relocking the lock box. The customer key may then again be made available to the postal patron from post office personnel at which time postage due, delivery charges, etc. may be paid in order to permit the patron to again receive the key and gain access to the lock box. Once the customer key is received by the patron the cycle may be repeated. That is, the patron may go to his or her lock box, open the box, remove the contents leaving the key in the lock associated with the lock box. The postal employee will again close and lock the box as well as retrieve the key.
For example, the U.S. Postal Service has specifications and criteria for such locks under the postal service identification No. 0306P key lock assembly, P/ND-1002980. Such locks typically require a postal worker to reset or release of the customer key from the lock and reset the lock to the locked position.
Providing a system which will enable postal employees to retrieve a customer key and lock the lock box after a postal patron has utilized the lock box is thus a desirable goal and need with respect to such postal lock boxes. Moreover, other businesses may desire to utilize such a lock system where, in order to have access to a particular lock box, the patron must first acquire the customer key from a qualified or a certified employee associated with an establishment. Such a protoscol provides an incentive and protocol for the patron to clear all accounts or otherwise attend to appropriate matters of business before obtaining access to a lock box. Needs of this nature have inspired the development of the present invention.
Briefly, the present invention relates to a lock construction with a customer lock plug and associated bolt which, when rotated by means of a customer key from the locked position toward the unlocked position will be precluded from counterrotation unless and until a release mechanism is effected. Removal of the customer key is also precluded until the plug is counterrotated to the fully locked position. Various release mechanisms are disclosed. For example, the lock may include a special internal locking tumbler that cooperates with a cam surface inside the lock and engages the cam surface in one or more detent positions, to preclude counterrotation. A release mechanism includes a special key or tool which engages the special locking tumbler and releases it from the cam surface detent position that precludes counterrotation. Upon such release the special locking tumbler and the lock plug may be manually or mechanically counterrotated. An alternative embodiment provides for a pawl (which assumes the function of the special locking tumbler) and ratchet mechanism (which assumes the function of the detent cam surface) that preclude counterrotation of the plug and key and which may be released by a pawl release tool or key.
Thus it is an object of the invention to provide a lock which is rotatable from the locked position toward the unlocked position and which is precluded from counterrotation back to the locked position pending release of the mechanism that precludes counterrotation.
It is a further objection of the invention to provide a lock mechanism which, when moved from the locked toward the unlocked position, is precluded from counterrotation but which may be released from a counterrotation by means of a separate tool or key.
It is a further object of the invention to provide a lock having a minimum number of parts yet which may be used to provide lock box security and control for various purposes include postal lock box control.
Yet another object of the invention is to provide a lock construction which enables a patron to utilize a customer key actuated lock on a one-time basis for removal of contents from a lock box.
Yet another object of the invention is to provide a lock construction having a minimum number of parts which is economical to manufacture, easy to use, and which may be used to provide lock box security for an institution.
These and other objects, advantages, and features of the invention will be set forth in the detailed description which follows.